1. Field of the Invention
The present invention relates to the stabilization of hydrogen peroxide in an aqueous alkaline medium, and, more especially, to such stabilization by incorporating a particular composition into an H.sub.2 O.sub.2 bleaching bath for materials based on cellulose fibers, for example a bleaching or simultaneous bleaching/desizing bath for the treatment of textile or tissue substrates.
By the term "desizing" is intended a treatment for the degrading of starch by means of an enzyme of the amylase type, or a preparation based on such an enzyme.
By "bleaching" is intended a treatment with hydrogen peroxide, H.sub.2 O.sub.2.
2. Description of the Prior Art
The stabilization of H.sub.2 O.sub.2 in relation to bleaching or simultaneous bleaching/desizing in an aqueous alkaline medium is well known to this art. Compare, for example, U.S. Pat. No. 4,294,575.
Bleaching by means of H.sub.2 O.sub.2 in an alkaline medium, whether carried out individually or simultaneously with desizing, is also well known to this art. See, for example, the French patents published under Nos. 2,497,244, 2,543,181 and 2,545,854, the above '575 U.S. patent, and the Japanese patent published under No. 57-39,280.
And U.S. Pat. No. 4,239,643 describes an anhydrous or essentially anhydrous composition to increase the stability of H.sub.2 O.sub.2 in an alkaline bleaching bath, including a combination of an alkali metal polyphosphate and an alkali metal salt of diethylenetriaminepentamethylenephosphonic acid of the formula: ##STR1## for example, a combination of sodium hexametaphosphate and a sodium salt of the acid (I). The composition described has the advantage of being compatible with non-starch sizing agents, based for example on polyvinyl alcohol or on carboxymethylcellulose, which may be combined with those of the starch type. It also presents the added advantage of enabling bleaching in the absence of sodium silicate.
On the other hand, it has disadvantages related to its anhydrous or quasi-anhydrous character, which, if not observed, renders it unsuitable for its intended use. Therefore, it is necessary to protect it against the risk of dilution by or exposure to water, both in storage and during transportation, and against the difficulties inherent in the storage or transfer of solid materials, such as, for example, the formation of lumps and the aggregation of these materials.